Adsorption - Advanced oxidation process (AAOP) for the heavy metals and organic matter removal from leachate using combined filtration -Fenton's and Photo-Fenton's treatment

Abstract

Design of cost - effective filtration unit was carried out to evaluate the efficiency of different filter media made of locally available materials to treat raw leachate. Four different filter media laterites, peat, bagasse and a mixture of all were considered as study filter media for the removal of Zinc, Nickel, Copper and Lead from raw leachate. The reactor exhibited a significant removal efficiency when the three-filter media were combined as a combination. A removal rate of around 83.0% and 64.12% was found for nickel and copper, respectively, with a combined filter medium. The order of heavy metal removal varied depending on the kind of filter media used. For combined filter media, the sequence was Ni > Cu > Pb > Zn. For bagasse filter media, it was Pb > Cu > Zn > Ni. For peat filter media, it was Ni > Cu > Pb > Zn. For laterite filter media, it was Zn > Cu > Ni > Pb. Insignificant removal of heavy metals was observed with bagasse in the current investigation and hence is not recommended for use as a filter medium. Pre-treated leachate was subjected to Fenton's oxidation and UV-Fenton's oxidation for organic matter removal. Green synthesized bleached laterite iron nanoparticles were used as a catalyst in the Fenton treatment. COD removal of 80.0% and 85.0% was observed with 0.5 g/L of nano iron catalyst and 500 mg/L of H₂O₂ and 100 mg/L of H₂O₂ on Fenton's oxidation and UV-Fenton's oxidation respectively. The synthesized particles were demonstrated to possess a catalytic function in the reduction of COD. Both Fenton's oxidation and UV-Fenton's oxidation exhibit pseudo-first-order kinetics with linear regression.

Keywords: Adsorption; Bioleached laterite iron nanoparticles; Fenton's oxidation; Filtration process; UV-Fenton's oxidation.